No. First, you'd need two priests, since Equilibrium triggers when the card is played, not when it resolves; since your first priest is a spell at the time, it's not yet a creature and can't be bounced. Second, you're paying 2B to put him down, getting BBB, then paying 1 to put the other one back in your hand. In other words, you've spent 3B to get BBB. You're now down one mana. There are ways to get infinite combos going with this card, but that's not one of them.